In this paper are reported the synthesis and antiprotozoalactivity in vitro of 24 1-methylbenzimidazole derivatives (13–36) substituted at position 2 with aminocarbonyl, N-methylaminocarbonyl, N,N-dimethylaminocarbonyl, ethoxycarbonyl, 1-hydroxyethyl and acetyl groups, some of them with chlorine atoms at the benzenoid ring. Compounds 13–36 were more active than metronidazole, the choice drug against